Braided Fabric Structure-Based Out-of-Plane Wearable Thermoelectric Generator for Body Heat Energy Harvesting.

Wearable thermoelectric devices exhibit great potential in utilizing the temperature gradient between the human body and the surrounding environment to harvest energy, providing a sustainable and maintenance-free power source for wearable applications. However, traditional two-dimensional (2D) flexible thermoelectric devices are inherently limited by their planar configurations, which restrict them to in-plane heat collection and hinder the effective capture of out-of-plane temperature gradients. This limitation often results in a reduced thermoelectric conversion efficiency in practical wearable applications. To address this issue, a unique braided fabric-based thermoelectric generator (TEG) with superior wearing comfort and mechanical flexibility was designed to harvest out-of-plane temperature gradients in this study. Segmented p- and n-type thermoelectric coatings were applied on the braiding yarn to fabricate thermoelectric legs. The braided fabric bracelet TEG containing 12 p-n pairs could generate a maximal open-circuit of 8.42 mV at a temperature difference of 30 K. This study presents an innovative approach that may facilitate the advancement of TEGs for practical wearable applications.